Actually, it's a reprint that has Elly feeling empty because her children are growing up.
Panel 1: Mike says "I'm takin' Lizzie across the street, Ma!"; that's because he's taking her across the street to where the playground is.
Panel 2: We see her wearing work gloves as she's doing the raking; she tells him to watch for traffic and look both ways as he crosses the street and to do so quickly.
Panel 3: Her silhouette looks on as they've crossed the street.
Panel 4: She frowns a Bug-Eyed Frown of Existential Terror and thought-bubbles "I can aee the empty nest already."
Summary: Thirty years later, of course, she's just as depressed, if not more so, that her nest will never empty. Knowing how ridiculous time made the fears and anxieties their younger selves had is the "neat" thing about knowing what will happen to these people.
ETA: Yahoo has updated how they handled comics again so I had to use a work-around to get the summary; it was either that or wait until one a.m. and head over to chron.com.